Numerical Modeling of Fluid Mud Transport in Estuaries

The movement of fluid mud has been cited as the most likely cause of rapid sedimentation in channels located in muddy estuaries. A time dependent, two-dimensional laterally-averaged cohesive sediment transport model is introduced which simulates the formation, movement and sedimentation of a fluid mud layer in the vertical plane. The model consists of a hydrodynamic module, supplemented by an algebraic stress/flux turbulence closure module, dissolved salt transport module, and cohesive sediment transport module which simulates the transport of both low sediment concentration suspension and fluid mud. The latter is modeled as a Bingham plastic. The properties of fluid mud are described by empirical relationships from experiments. By comparing the predictions with analytical solutions and field measurements, each module of the model was verified and generally good agreement was obtained.